Sand blast pressure tank



F. J; HULL SAND BLAST PRESSURE TANK July 28, 1931.

Filed July 3, 192 8 5 Sheets-Sheet l July 28, 1931. HULL 1,816,583

' SAND BLAST I RESSUREi TANK Filed Ju ly :5. 1928 s Sheets-Sheet 2 July 23, 1931. 11111111 1,816,583

SAND BLAST PRESSURE TANK Filed Jl rly 5. 1928 5 Sheets-Sheet 5 July 28, 1931. F J HULL 7 1,816,583 A I SAND BLAST PRESSURE TANK Filed July :5, 1928 5 Sheets-Sheet 4 z l I 9 '3 1 E 449 g 51 z v I E E z I 6'6 July 28, 1931. F. J. HULL ,8

sum BLAST PRESSURE TANK Filed July 5, 1928 5 Sheets-Sheet 5 Patented July 28, 1931 UNITED STATES PATENT errlcr.

rosrnn J. HULL, 0F HAGERSTOWN, MARYLAND, assrenon T0 rANeBoRN oonrona- 'IION, or HAGERSTOWN, MARYLAND, A CORPORATION or MARYLAND SAND BLAST rnnssunn TANK Application filed July 3,

In the Operation of sand blast apparatus a considerable loss of efiiciency as to the space occupied by the apparatus and the power expended in providing compressed air for the blast has resulted from the waste space in the pressure tank, from which the abrasive is fed to the mixing valve and hence to the hose which leads to the nozzle, or nozzles, from which the abrasive stream is projected against the work.

.It will be understood that the tanks, in order to give the cheapest construction which will resist the pressures employed, are, in accordance with the existing practice, inade cylindrical, the inlet valves for the abrasive being one at the center of each of the transverse or horizontal walls at the top and center, and the outlet to the mixing valve is formed in, or extends through, the

cylindrical side wall at the bottom. The

waste space referred to is partly due tothe nature of the material handled, the abrasive ordinarily used having an angle of flow of.

about forty-five degrees, whereas the angle of flow of a' liquid closely approaches zero,

i. e., it varies but slightly from the horizontal. A further cause ofwaste space in the tank is due to the impossibility of projecting the material by gravity from the valve open ing outwardly to the sides of the tank, without likewise deflecting its course downwardly. I For this reason the outer portion of the tank entirely around the circumference at p the top immediately below each horizontal partition is at no time filled with abrasive.

This waste space is, as a matter of fact, due to the same cause, i. e., the angle of flow of the abrasive, otherwise, i. e., if it possessed the fluid properties of a liquid, the-tank could be filled level to the top.

It will be noted, therefore, that the waste space is of two different kinds or classes, i. e., the unfilled wastespace or dead air space around the circumference at the top,

; and the dead abrasive space at the bottom of each chamber. Thelatter is the space filled with abrasive which cannot be discharged through the outlet. The unfilled waste space, or dead air space, not only detracts from the efliciency of the apparatus 192s. .Srial No. 2903422 by necessitating a higher tank, as does the dead abrasive space, but it further detracts from the eliiciency v of'v the apparatus,

as this unfilled space inust'be filled with compressed air after each refilling of the tank, which refilling operation, as Wlll be easily understood, involves as a necessary to reduce ciency of the machine and reduce the size of the tank having .agiven predetermined discharge capacity. By the revision of the apparatus in accordance with the invention a tank of the same capacity, i. e., two hundred fifty cubic feet discharge, is reduced to a height of ten feet, the waste space being reduced from six hundred fifty-four to two iundred fifty-two cubic feet.

In the accompanying drawings I have illustrated a sand blasttank embodying the features of myinvention inthe preferred form. f

In the drawings: i

Figure 1 is, a'general view of the tank in the nature of a side eicvation;

Figure 2 is a top plan view of the apparatus. 7

l igure 3 is a horizontal. section on the line 3-3 of Figure 1, looking downwardly.

Figure 4 is'a vertical section on the line 44: of' Figure 2. j V

Figure 5 is a fragmentary View showing the compressed air supply andrelease connections and control for the'upper chamber of the tank.

Figure 6 is a diagrammatic View in the nature of a central vertical section of the tank, indicating the waste spaces, consisting of dead air space and dead abrasive spacer periphery of the tank.

, Figure 7 is a top plan view of the same, also diagrammatic;

. Figure 8 is a diagrammatic view showing the waste spaces, comprising dead air space and dead abrasive space, in accordance with the previous practice.v

Figure 9 is a top plan view of the tank shown in Figure 8.

Figure 10 is a diagrammatic view in the nature of a plan showing the manner of supplying air to toe cylinder valves to'operate the same.

Figure 11 is a diagrammatic view in the nature of a plan illustrating the manner of supplying air to the mixing chambers and to the lower chamber of the tank.

Referring to the drawings by numerals, each of which is used to indicate the same or similar parts in the different figures, the

apparatus, as shown, comprises a sand blast pressure tank 1 divided into two chambers, referred to herein as the upper. or primary chamber 2 and the lower or secondary cham ber 3. The tank, in accordance with the regular practice, has an upwardly concave head l serving as the top wall of the upper chamber and an upwardly concave central partition 5 serving as the top wall of the lower chamber and the bottom wall of the upper chamber.

In accordance with the previous practice there was an abrasive admission valve inthe.

center of the top wall 4 of the .upper chamber. In the apparatus of the invention there is a series of such valves 9.arranged around the chamber and spaced away from the center." These valves cooperate with valve seats 6 surrounding the valve openings 7. It will be noted from Figure 6 that.

while the valves are spaced away from the center of the concavity they are not raised .perceptibly above the lowest level of the top wall 4.

In accordance with the invention, the top her 3 is also provided with abrasive admission valve openings 17, likewise spaced away from the center and arranged along the These valve seats are closedby abrasive valves 19 cooperating with valve seats 16 and the valve and valve openings are, in the form of the invention shown, three in number.

The number of valve openings and valves used is immaterial in both instances, though the, valves of the two series preferably correspond.

In accordance with the preferred form of invention the abrasive from the lower chamberis fed to the hose lines which, in turn, lead to the sand blast nozzles by way of mixing valves 70. As shown, there are two of these mixing valves corresponding to each of the abrasive feeding valves 9 and 19 respectively. l/Vhile this arrangement is found convenient, it is not essential to the lnvention. In the apparatus shown, there are three of the valves 9 for admitting abrasive to theupper chamber 2 and three of the valvesl9 for admitting abrasive from the upper chamber 2 to the lower chamber 3, and there are six of the mixing valves 70 for mixing the abrasive with compressed air in accordance with the well known practice and feeding the mixture of abrasive and compressed air to the hose whereby it is fed to the nozzles. These six mixing valves are connected to the outer cylindrical wall of the tank 1 at the bottom b passages 72, Figure 6, the abrasive being caused to flow by gravity from the tank intolthe mixing valves, as best illustrated. in Figure 6.

Figure 6 shows the position of rest of the.

dead abrasive when the supply of abrasive subject to discharge has been exhausted. In this figure the dead abrasive in the upper chamber is indicated by referencecharacter 90, the area in the upper chamber from;

which the abrasive may be discharged by reference character 91 and the dead air space in both chambers by reference character 92. The deadfabrasive iiithe lower chamber is indicated by reference character 93.- The area in the lower chamber from which the abrasive is discharged is indicated by referencecharacter 94.

Figure 8 shows for the purposes of comparison a tank arranged in accordance with the previously existingpractice, from which tank the available dischargeable abrasive hasbeen discharged. In this figurethe dead abrasive in the upper chamber is indicated by reference character 95, the dead air space in both chambers by reference character 96, and. the 'area previously occupied bv the abrasive, which has beenv discharged from the upper chamber, by reference character 97, and from the lower chamber. by referen'ce character 98. The dead abrasive in the lower chamber is indicated by reference character 99; Inthis apparatus the abrasive filling valves. are indicated by reference character 9 inthe center of the upper partition 4/ or top of the tank, and by, 19" in the center of the partition 5, which separates the upper and lower chambers and the single mixing valve at the bottom of'the lower chamber connected tothe side wall thereof,

Air under pressure is led from any convenient source byway of an air pressure supply pipe 47, Figure 11, to upright air pressure pipes 25, Figure 2, which, in the :nachine shown, are three in number, one for each of the lilling'valves in either set of vaives in either of the heads 4, 5, i. e., the valves 9 or 19, though the exact arrangement and number of'pipes and valves is iminaterial.

The upright pipes are connected at the bottom by branch nines 71, see Figure 1, to the respective mixing valves 70, there being in the form of machine shown two.

mixing valves for each ofthe upright pipes 25 and for each of .the filling valves in each set.

Each upright pressure pipe 25 is also connected by apipe 22 to the lower'pressure pet valve 65 which is'operated by a piston 60' to open. and close alternately ports 63 and 66 respectively'above and below the valve. T he port 63 connects the passage 49 by way of valve passage 51 and the pipe 54: to the filler valve pipe 12, Figures 4 and 5,

I, which operates the upper filler valve 9, it

being understood that there is a cylinder valve and passages as described for each of the respective filler valves 9. The pipe 12 opensbeneath the valve through a cup 10 and operates the corresponding valve 9 in a well known manner, see above mentioned application of Foster J. Hull, also serving to supply air under pressure to fill the tank at the proper time in accordance with the practice.

Each pipe 5% contains a non-return valve or check valve 55, Figure 5, which opens toward the tank admitting air under pressure to the tank by way of the pipe 5-1 and 12 p when the valve seat 63 isopenedby the double valve (35 and when the valve seat 63 close l and the exhaust seat 66, is open, the air is exhausted from the upperchamber 2 by way of the pipe 56 which is controlled a check valve 57, it being understood that when the exhaust seatfifi is opento. the exhaust passage andthe pressure seat is closed, therev is no tendency for pressure air from the chamber2 to pass the check valve and re-enterjthe tank as thevpressure in this directionis equalized. The air from the tank will, therefore, be freelyexhausted by way of the pipe56, check valve 57,dow-nward through pipe ,54 to exhaust seat 66 and the exhaust passage 50.

The mixer valves 70 are connected to the tank at the bottom by passages 72, being spaced around the periphery of the tank in:

any suitable manner as indicated in Figure 3.; The abrasive is supplied by gravity to these mixer valves, air pressure being maintained in thetank in any suitable manneras by way of passage 22, and pressure air is further supplied to the mixer valves by way of the upright pipes 25 and branch pipes 71 supplying astream of mixed abrasive and air under pressure, which can beconducted from each valve by way of a hose 73, Figure l, to be directed against the work by means of a no'zzleor the abrasive stream maybe distributed from each mixing valve to several. different nozzles.

In operation, each of the cylinder valves 35, one foreach pipe 25, is controlled as to the position of the piston GOJand hence as to the position of the double poppet valve 65, effecting the opening and closing of the pressure seat 68 and the exhaust seat 66 by;

means of a supply of air under pressure led to the cylinders 35 by way of afismall pipe 43, the supply of air to said pipes 43 being controlled in any suitable 'nianner as by means of a three-way valve i1 which may be automatically, or otherwise operated, as preferred. I

Th s valve controls and determlnes the supply of air to the pipe 43 from an air. 7

pressure-supply pipe which leads to the valve from a suitable source of air pressure supply and also controls the release of the air from the pipe 43 and from the cylinders by way of the exhaust or release pipe 81, also connected to the valve 41. The pressure in the pipe 80 may be higher than in pipe 47, but this is not necessary to the operation of the machine.

When the tank is in operation a quantity of-abrasive is supplied to the head 4:, the

same being delivered thereto in anysuitable manner. This is piledupon the head ITo admit the abrasive to the upper chamber 2,

which is in the nature of an air lock, the pressure in tlllS chamber, which at the time of transfer is equal to working pressure in the lower chamber, must be released; To accomplish this-the three-way valve 41 is turned to aposition in which the pipe 43: is opento the exhaustSl. This relieves the pressure on the top of the piston 60, Figure 1, and permitsit to raise in response to the air pressure beneath it, i. e., in the cylinder 85, it being understood that theoperation described takes place in. each of the cylin ders 35 and in connection with each of the fillingvalves 9. I 7

J closing the exhaust seat 66.

The upward motion of the piston 60 moves valve 65-upwardly closing the pressure seat 63 and opening the exhaust seat 66' to the exhaust pipe 50, which provides for release of the air from the tank by way of the pipes 56, see particularly Figures 7 and 5, through the check valve 57 and by way of the lower branch of the pipe 54', to the valve passage 51 where it passes to the exhaust pipe by way of the exhaust seat 66.

When the pressure in the chamber 2 has been sufficiently exhausted the filling valves 9 open in response to the pressure of the abrasive thereon and as inuch abrasive as can be admitted by gravity in this way is admitted to theupper chamber 2. In this connection it will be observed that the inflowing abrasive is excluded from, i. e., it cannot besupphed to the portions of the upper chamber indicated by shading 92 in Figure 6, and referred to as the dead air space.

When the upper chamber 2 has been filled as far as can be accomplished in this way, the valve 41 1s turned and air is admitted from the supply '80 to the pipe 43, the exhaust 81 being closed. The downward pressure on the top of the-pistons 60 thus established by admission of air from the pipe l3 assisted in the initial portion of tho oper' ation by the downward pressure on the top of the valve 65, which is closed against the pressure seat 63,moves the valve 65 downwardly, opening the pressure seat6-3 and Referring again to Figure 5, it will be understood" that when the exhaust is closed and the pressure port 63 is opened, air under pressure will enter the chamber 2 of the tank, going from the valve passage 51 "by way of the pipe 54 through the check valx e 55, Figure 5, which it opens, and to the pipe 12 which enters the cup ,10 beneath the valve.

it being unrlerstoodthat there are three of the valves 9 and the operating means therefor in the apparatusshown.

It will be understood that at this time, the check valve 57 being closed by the air pressure in pipe 54, the entrance of the air 'to the tank by way of the pipe 56-is pre- VVhen the pressure in theupper vented. chamber 2 has been sufficiently built up, it being understood that this chamber is now filled with abrasive, the pressure of the abrasive on the valves 19 in addition to the air pressure thus built up, serves to open;

the transfer valves 19 against the pressure of the spring 20 and the pressure of the air in the'chamber 3, which is balanced by the pressure which has just been established in the chamber 2. The valves 19 being thus opened, the abrasive flows from the chamber 2 to the chamber 3, so far as the transfer can be effected by gravity. The condition in the chamber 2 being at the end of the transfer operation, i. e., the operation of transfering the abrasive from the chamber 2-to the chamber 3, represented by the diagram, Figure 6, the dead abrasive 1111116. upper chamber, i. e., that which cannot be transferred from the upper to the lower chamberv being indicated by reference char-- acter 90 in the upper chamber.

When the transfer operation has been completed the controller valve 41 is again nozzles, not shown,are supplied with mixed abrasive and air by way of the hose lines 73, one or more of which is connected to each of the mixing valves70 of which, in

' the form of the invention shown, there are six, two mixing valvesbeing supplied with pressure air from each of the air pressure pipes 25. These mixing valves 70 are distributed around the peripheryof the tank with substantial uniformity, being connect ed to the sides of the tank at the bottom by way of pipes or passages 72. Inthis way the available volume of abrasive which can be removed from the lower chamber by way of the mixing valves is greatly increased as compared to the previously existing practice, the position of the dead or remaining abrasive being indicated at 93- in Figure 6,

which shows the condition of the abrasive in the lower'chamber when the available abrasive in thatchamber has been exhausted. The abrasive is exhausted from area 94'.

The corresponding condition, in accordance with the previously existing practice is illustrated in Figure 8,'the dead abrasive in the lower chamber being indicated at 97 in said chamber. V 7

It will be understood that, the foregoing. description. ofthe operation. relates to the supplying of abrasive by gravity to the upper chamber of the tank andto thetransfer by gravity of the abrasive from the upper'to the lower chamber, and to the feeding of from which it is propelled by the air under pressure supplied directly to the mixing valves from an outside source, being thus projected through the nozzle, by which it is directed against the work.

It will also be understood that the various features and details of the mechanism may be widely varied withinthe scope of the in-.

abrasive by gravity to the mixing valves,

vention and that any preferred means of handling the abrasive may be subsituted for the gravity means as to part of the machine without affecting the operation of the other parts of the machine.

The main object of the invention is to equalize the distribution of the abrasive and increase the capacity of the tank by increasing, proportionately to the total volume of the tank, the volume to which the abrasive is supplied and from which it is removed as the tank is filled and discharged.

I have thus described specifically and in detail an air blast pressure tank apparatus embodying the features of my invention in the preferred form in order that the nature and manner of operating the same may be clearly understood, however, the specific terms herein are used descriptively rather than in a limiting sense, the scope of the invention being defined in the claims.

WVhat I claim as new and desire to secure by Letters Patent is:

1. A sand blast apparatus comprising a tank having upper and lower chambers, means for supplying air under pressure to the upper chamber and releasing it therefrom, means for supplying air under pressure to the lower chamber, means for mixing air under pressure and abrasive connected to the lower chamber to receive abrasive therefrom, means for admitting abrasive to the upper chamber and a'plurality of valves for transferring the abrasive from the upper chamber to the lower chamber by gravity, some of said valves being spaced outwardly from the center and spaced apart to equalize the distribution of abrasive as admitted to the lower chamber.

2. In a'sand blast apparatus, a tank having an upper chamber and a lower chamber, transverse walls at the top of each said chamber, means for supplying air under pressure to the upper chamber and releasing air therefrom to relieve the pressure therein, means for supplying air to the lower cham ber, air and abrasive mixing means connected to the lower chamber and means for supplying air to said mixing means, a plurality of valves in the top wall of the upper chamber admitting abrasive thereto by gravity, some of said valves being spaced outwardly from the center, said valves being spaced apart to equalize the distribution of abrasive in the upper chamber and means for transferring the abrasive from the up per chamber to the lower chamber.

3. In a sand blast apparatus, a tank having an upper chamber and a lower chamber, transverse walls at the top of each said chamber, means for supplying air under pressure to the upper chamber and releasing air therefrom to reduce the pressure therein, means for supplying air to the lower chamber, means for mixing air and abrasive connected to the lower chamber and means for supplying air to said mixing means, a plurality of valves in the top wall of the upper chamber to admit abrasive thereto bygravity, some of said valves being spaced outwardly from the center and said valves being spaced apart to equalize the distribution of abrasive in the upper chamber and means for transferring the abrasive from the up-.

chamber and to the lower chamber compr1sing a plurality of upright air pressure pipes, means for releasing air from the upper chamber, passages connecting each of said upright air pressure pipes'to the upper and lower chambers, a plurality of mixing valves one said valve being connected to each ofsaid upright pipes to supply air under pressure to the mixing valves, said mixing valves being connected to the lower chamber to be supplied with abrasive therefrom by gravity, said connections being spaced apart, an abrasive admission valve for each of said upright pipescontrolled by the compressed air therefrom spaced apart and admitting abrasive by gravity to the upper chamber, a corresponding number of abrasive admission valves spaced apart and controlled by the compressed air admitting abrasive by. gravity from the upper to the lower chamber and arranged around the lower chamber.

5. A sand blast apparatus comprising a container having upper and lower chambers, means for supplying, air under pressure to the upper chamber and releasing it therefrom, means for supplying air under pres sure to the lower chamber, a plurality of means for mixing air under pressure and abrasive and connections for said respective means to the lower chamber whereby the mixing means receivev abrasive from said 1 chamber, said connections being spaced apart, a plurality of valves for admitting abrasive to the upper chamber, and a plurality of valves for transferring the abrasive from the upper chamber to the lower chamber by gravity, both sets of abrasive valves being so spaced apart and distributed as to equalize the distribution of the abrasive into a series of piles over substantially the entire bottom surface of each chamber.

Signed by me at Brentwood, New York, this 18th day of June, 1928.

ros'rnn ,J. HULL. 

